1. Field of the Invention
The present invention relates to an optical pickup provided in optical disc drives for reading information recorded on a recording surface of an optical disc or for recording information thereon.
2. Background Art
Conventional objective lens driving means provided in the optical pickup of an optical disc drive is composed of a moving part on which an objective lens is mounted, support members for supporting the moving part, focusing coils, tracking coils, a yoke, and magnets.
When a drive current is applied to the focusing coils, electromagnetic force is produced by the interaction of the current with the magnetic flux produced by the magnets. The electromagnetic force drives the moving part in a focusing direction, which is either toward or away from the optical disc surface. Similarly, when a drive current is applied to the tracking coils, electromagnetic force is produced by the interaction of the current with the magnetic flux from the magnets. The electromagnetic force drives the moving part in a tracking direction, which is along the radius of the optical disc.
An example of a conventional optical pickup having the aforementioned configuration is disclosed in Patent Document 1. In the optical pickup disclosed in Patent Document 1, the tracking coils and the focusing coils are fixedly attached to a lens holder. A single magnet is magnetized with three pairs of an N pole and an S pole alternately. The publication also discloses a configuration in which three magnets are combined.
Patent Document 1: JP Patent Publication (Kokai) No. 10-334486 A 1998 (page 4, and FIGS. 1 and 2)